1. Field of the Invention
This invention relates to the field of stretcher bar frame members for artists' canvases, needlepoint backing material, and the like, and more particularly to a stretcher bar system and kit which comprises corner bracket units which matingly receive stretcher bar rail material, and which can be easily assembled by the artists to form stretcher bar frame members of any desired size.
2. Description of the Prior Art
There are countless professional and amateur painters in the U.S. and around the world. Painting with oil paints (and more recently with acrylic and alkaloid paints) on canvases stretched across wood frames dates back hundreds of years, and continues to be the painting surface of choice for many. The ability to build strong, yet economical frames, which frames allow the canvas to be tightly stretched and attached thereto remains a concern. Many artists purchase pre-assembled frames with the canvas already attached and stretched thereto. However, some artists desire frame sizes of different dimensions and/or prefer to prepare their own canvases.
The Applicant is aware of two relevant patents. U.S. Pat. No. 4,565,020 to Beatriz et al. discloses the use of right angle corner members into which ordinary lumber pieces for the frame can be engaged and slidably held in place by screws passing through slots formed in the right angle corner member. The frame members have exposed mitered corners which can be pushed outwardly by bolts inserted into threaded apertures or wedges inserted into compartments to further stretch the canvas. The Beatriz et al. patent also teaches that the right angle corner members will tilt the upper surface of the frame lumber such that the canvas rides on the outer edges of the frame lumber, and does not overlay the entire upper surface of the frame lumber. One problem with the Beatriz et al. device is that since the corners of the frame do not tightly hold the wood frame members together, and the tension of the canvas is required to prevent the wood frame members from moving relative to each other. Another problem is the requirement that the corners be carefully mitered.
U.S. Pat. No. 3,651,854 to Terna discloses a stretcher for canvas or other materials which is assembled from mitered cut profile strips which are assembled with angle irons into the frame. The outer perimeter of the strips are formed to have a raised perimeter edge, which lifts the stretched canvas, so that it does not contact with the entire upper surface of the strips. The Terna frame requires specialized profile strips, which would likely be costly. Moreover, the corners must be carefully mitered.
There accordingly remains a need for economical and sturdy frame members for artists canvases, which can be used by the artist to easily form strong frames, having perfect square corners, for artist canvases of any size and dimension, for needlepoint usage, and for other materials as well.